Zurich prosecutors have dropped an investigation of former Swiss government member Christoph Blocher after failing to find evidence he played an illegal role in leaking confidential bank data, prosecutors said in a statement on Thursday. The case, dating to 2012, involved information on currency deals by the family of now-former Swiss National Bank Chairman Philipp Hildebrand that was leaked by a Sarasin employee to a lawyer with ties to Blocher's political party.